Certain medications are more effective when they are administered to a patient by injection. One such medical condition which shows improved treatment with several daily injections is the treatment of diabetes with insulin. Unfortunately, the required multiple injections not only cause physical and psychological pain, but also raise the possibility of infection.
Various pump devices have been proposed to either slowly administer a continuous flow of insulin or provide several intermittent injections over time. These devices generally use a needle, which is inserted through the skin. Due to the threat of infection, the needle must be discarded after use, and a new needle inserted in a different location each day. To meet these problems, catheters have been designed for implantation through the skin to deliver the insulin. Unfortunately, such catheters have their own shortcomings and can sometimes become infected, thrombose or become clogged, reducing or stopping the flow of insulin. Occasionally, without any apparent reason, the subcutaneous tissue of a diabetic patient will begin to degrade and inactivate insulin, reducing its usefulness.
To solve these problems, implantable insulin infusion devices have been proposed. Such devices are implanted under the skin, with a tube leading into the peritoneal cavity. This avoids the difficulties of insulin inactivation by subcutaneous tissue, clogging and the threat of thrombosis. It has also been found that insulin administered intraperitoneally is quickly carried to the liver, the natural delivery point for insulin produced by the pancreas. This form of administration also has the side benefit of minimizing ketosis and hyperglycemia.
The devices which have been proposed for such administration have a pierceable septum which is either outside the patient or is located immediately below the surface of the patient's skin. However, in attempting to solve one problem, a new problem is created. After the pierceable septum of such a device becomes worn through use, it must be surgically removed and replaced, thereby exposing the patient to pain, discomfort and possible infection. No means is provided for replacing the septum after it has become worn through repeated injections. Nor is any means provided to protect the patient from infection during such a replacement.
Accordingly, it would be desirable to provide a device and medication delivery system which avoids the shortcomings of the prior art, yet provides for a safe and effective way of delivering a medication to the patient percutaneously. Such a device and system should have parts which can be easily and safely replaced as they become worn through use and should also protect the patient against infection while a part is being replaced. Means should also be provided for connecting with a pump for continuous administration of medication. The present invention meets these desires.